After thinking on this for a few days (I like the idea of an underground village) I've decided a solar-powered MFFS system is the best way to go (for me anyway). Don't even need a field projector, just extractor, capacitor, security station, and defense station. It instantly kills all mobs within a radius of up to 64 blocks. I'd put the capacitor and extractor closer to the surface (the capacitor can power modules up to 80 blocks away with upgrades), for less cabling from the solars and less pipe or whatever you use to get forcicium into the extractor. I have a setup like this in my floating island base in my extreme hills world, it's fun to look at distant endermen and watch them disappear when they teleport into range to be killed. It also kills neutral mobs if you set it to, so watch out, it can empty your village if you're not paying attention when you set it up.